Patent GB-1057069-A (GB)
Title: Flame failure control for a vapor generator burner system
IPC: F23N5/08
Filed: 1963-11-06
Abstract: 1,057,069. Controlling burners. COMBUSTION ENGINEERING CO. Nov. 6, 1963 [Nov. 29, 1962], No. 43783/63. Heading F4T. [Also in Division G1] A system for controlling the burners 16 of a vapour generator comprises a valve 28, Fig. 3, controlling the fuel to each burner, a sensor 70, Fig. 4, sensing the ignition energy of an igniter torch 56 associated with each burner, a flama sensor 92 for sensing the flame of each burner and a sensor 201, Fig. 1 (not shown), for sensing the pressure in the fuel pipe 22 supplying all the burners, the arrangement being that each fuel valve 28 is opened by an electric impulse from the ignition energy sensor 70 and is held open by an electric impulse from any of the three sensors. The fuel valve 28 is actuated to open slowly and close rapidly by a piston 32 moved against the action of a spring 36 by a fluid supplied by a pump 40 driven by an electric motor 42. The stem of the valve carries an arm 46 which opens a limit switch 44 to de-energize the motor 42 when the valve is open. A solenoid valve 48 is opened to relieve the fluid pressure and allow the fuel valve 28 to close. The flame sensor comprises a photo-sensitive electron tube 94 and a receiver 96 for transforming the signal from the tube into means for closing contacts 98 to energize a relay 100. The ignition energy sensor 70 comprises a pair of pressure taps 72, 74 conveying the pressures in the igniter torch head 56 at a point adjacent a fuel atomizer nozzle 58 and at a point near the mouth of the head to a diaphragm 78 adapted to close contacts 82 to energize a relay 84. The pressure sensor 20<SP>1</SP> is a switch which is actuated by a fuel pressure representing 30% of the rated pressure for the burners. Each burner has a control circuit as shown in Fig. 5. In order to start a burner its igniter torch is first ignited by a spark plug 60 and contacts 116 are then closed manually or by a computer. The ignition energy sensor 70 closes the contacts 86 to energize the motor 42. Consequently, the fuel valve opens and limit switch 44 opens to de-energize the motor in the fully open position of the valve. The ignition sensor 70 also opens contacts 88, and the pressure sensor opens contacts 21<SP>1</SP> and, if the burner ignites, the flame sensor opens contacts 104. These contacts 88, 104 and 21<SP>1</SP> are in series with the solenoid 49 of the relief valve 48 and therefore if one only of these contacts remains open the solenoid remains de-energized and the fuel valve 28 consequently remains open. If, however, all three contacts close in consequence of no signals from the ignition sensor, the flame sensor and the pressure sensor the solenoid 49 is energized and the fuel valve 28 closes. The solenoid 49 can also be energized by closing contacts 122 manually or by a computer. The arrangement of contacts 45<SP>1</SP> closed when the fuel valve 28 is from 90 to 100% open, contacts 21 closed by the pressure sensor and contacts 102 closed by the flame sensor re-energizes the motor 42 if the operating fluid of the pump leaks from below the piston 32. The fuel supply to all the burners is controlled by a fuel valve 24 controlled by the circuit shown in Fig. 6. The burners are arranged in three elevations I, II, III in the furnace, each elevation comprising four burners A, B, C, D, one at each corner of the furnace. The circuitry is arranged so that the fuel valve 24 remains open if the flame sensors and the ignition sensors of two or more burners of each elevation I, II, III indicate the presence of flame and that the energy of ignition is sufficient but if the flame and ignition sensors of three burners of each elevation indicate as flame and insufficient ignition energy the fuel valve 24 is energized and closes. Each ignition sensor 70 opens two contacts 90, 90<SP>1</SP> when the igniter torch is ignited and each flame sensor 92 opens two contacts 106, 106<SP>1</SP> when the burner 16 is burning. The contacts 90A, 90B, 90C, 90D and 90<SP>1</SP>A, 90<SP>1</SP>B, 90<SP>1</SP>C, 90<SP>1</SP>D for each elevation I, II, III are arranged as shown in Fig. 6 in the supply line to a relay 132 actuating a switch 136 in the supply line of a relay 142 adapted to actuate the fuel valve 24 and the contacts 106A, 106B, 106C, 106D and 106<SP>1</SP>A, 106<SP>1</SP>B, 106<SP>1</SP>C, 106<SP>1</SP>D for each elevation I, II, III, are arranged as shown in the supply line to a relay 134 actuating a switch 138. The circuit also includes a bank of parallel contacts 45A, 45B, 45C, 45D each of which is opened by the stem of a fuel valve 28 for each burner when the fuel valve is fully open. Contacts 148 are arranged in parallel with the contacts 90A, 90B. 90C 90D and 90<SP>1</SP>A, 90<SP>1</SP>B, 90<SP>1</SP>C, 90<SP>1</SP>D for each elevation and are closed manually or by a computer when it is desired to remove a burner elevation from service.